Lennox error code 411 indicates a problem with the furnace's flame sensor. This error code occurs when the furnace is unable to detect a flame, which can be caused by a dirty or obstructed flame sensor. A dirty flame sensor can be cleaned with a soft cloth and some rubbing alcohol. If the flame sensor is obstructed, you will need to remove the obstruction and then restart the furnace.
1. Check that the outdoor unit is properly connected to the indoor unit
- Open the outdoor unit's front cover and ensure that the power cord is plugged securely into an outlet.
- Open the indoor unit's front cover and ensure that the power cord is plugged securely into an outlet.
- Verify that the red and green power indicator lights on the outdoor unit are on.
- Verify that the red and green power indicator lights on the indoor unit are on.
- If the red and green power indicator lights on the outdoor unit are not on, check to see if the power cord is plugged into the outdoor unit correctly. If the power cord is not plugged into the outdoor unit correctly, plug it into an outlet and then plug the indoor unit into the power cord.
- If the red and green power indicator lights on the indoor unit are not on, check to see if the power cord is plugged into the indoor unit correctly. If the power cord is not plugged into the indoor unit correctly, plug it into an outlet and then plug the outdoor unit into the power cord.
- If the red and green power indicator lights on the outdoor unit are on and the power cord is plugged into the indoor unit correctly, then the indoor unit is not receiving power and the lennox error code 411 may be the cause. To fix this, either connect the indoor unit to an alternate power source or replace the indoor unit.
2. Make sure that the outdoor unit is turned on
- Verify that the power is on to the outdoor unit.
- Check the breaker panel to see if the outdoor unit is properly connected to the power supply.
- Check the power cord to make sure it is not damaged.
- Verify that the unit is receiving power from the breaker panel.
- If the unit is not receiving power, contact an electrician to check the connection and/or wiring.
- If the power is on and the unit is receiving power, check the unit’s power switch and/or the fuse.
- If the unit is still not turning on, contact an authorized service technician.
3. Clean the outdoor unit's coils
The first step is to turn off the power to the unit. Then, use a pair of pliers to remove the screws that secure the coils cover. Be careful not to touch the coils themselves. Once the cover is off, use a vacuum cleaner to clean the coils. Finally, replace the screws and cover.
4. Replace the outdoor unit's filter
- Turn off the power to the outdoor unit.
- Disconnect the outdoor unit's power cord from the electrical outlet.
- Remove the outdoor unit's cover.
- Remove the outdoor unit's filter.
- Clean the outdoor unit's filter with a filter cleaner.
- Install the outdoor unit's filter.
- reconnect the outdoor unit's power cord to the electrical outlet.
- Turn on the power to the outdoor unit.
5. Check the outdoor unit's refrigerant levels
- Open the outdoor unit's refrigerant access panel.
- Check the refrigerant levels.
- If the refrigerant levels are too low, add refrigerant.
- If the refrigerant levels are too high, reduce the unit's cooling capacity.
6. Check the outdoor unit's compressor
1.Check the power supply to the outdoor unit and make sure that it is working. 2.Check the outdoor unit's compressor for service by testing the compressor's motor with a voltmeter. If the compressor's motor is not working, the outdoor unit's compressor may need to be replaced. 3.If the compressor's motor is not working, verify that the outdoor unit's compressor fan is working by testing the fan's power with a voltmeter. If the fan's power is not working, the outdoor unit's compressor fan may need to be replaced. 4.If the fan's power is not working, verify that the outdoor unit's air filter is clean and installed correctly. 5.If the air filter is not clean or installed correctly, the outdoor unit's compressor may not be able to function properly. In this case, the outdoor unit may need to be replaced.